Questions and Answers
What type of organism is bacteria?
What are the three shapes of bacteria?
Bacillus, Coccus, Spirillum
What components are found in the cytoplasm of bacteria?
Ribosomes, storage granules, metabolic enzymes
The thick gelatinous layer that surrounds some bacteria is called a ___
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What is the primary function of Pili in bacteria?
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What is the structure of a Gram-positive cell wall?
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Describe the structure of a Gram-negative cell wall.
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What is the main method of bacterial reproduction?
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What are the three types of DNA exchange in bacteria?
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What is transduction?
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Penicillin is mainly effective against Gram___ bacteria.
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Study Notes
Bacteria Overview
- Prokaryotic microorganisms lacking internal membranous organelles like a nucleus, mitochondria, or lysosomes.
- Exhibit diverse shapes: bacilli (rod-shaped), cocci (spherical/ovoid), and spirilla (spiral/wavy forms).
Bacterial Structure
- Cytoplasm: Dense medium containing ribosomes, metabolic enzymes, and storage granules for glycogen, lipids, or phosphates.
- Nucleoid: Contains a single, circular DNA strand (double-helical) holding 3,000 - 6,000 genes, located within the cytoplasm.
- Plasmid: Small circular DNA molecule carrying genes separate from the main chromosome, often involved in antibiotic resistance.
- Capsule: A thick gelatinous layer surrounding some bacteria, composed of polysaccharides, providing defense against the immune system and increasing virulence.
- Flagella: Motility structures made of three parts (Basal granule, hook, filament) anchored to the cell membrane and cell wall.
- Pili: Tubular protein extensions used for bacterial clumping and genetic material exchange during conjugation.
Gram Staining and Cell Wall Structure
- Gram-Positive: Characterized by a thick peptidoglycan layer outside the plasma membrane; susceptible to penicillin which disrupts cell wall production.
- Gram-Negative: Comprised of a thin peptidoglycan layer and a second outer layer of carbohydrates and lipids, providing resistance to certain antibiotics.
Bacterial Reproduction
- Transverse Binary Fission: Asexual reproduction process involving DNA replication and division into two identical cells by septum formation; can occur rapidly under optimal conditions, potentially producing up to 250,000 cells in 6 hours.
Horizontal Gene Transfer Mechanisms
- Transformation: Uptake of fragments of DNA from a disrupted bacteria by another bacteria.
- Conjugation: Direct transfer of genetic material between two bacteria via a sex pilus.
- Transduction: Transfer of genetic material mediated by bacteriophages (viruses that infect bacteria).
Key Facts
- Penicillin is specifically effective against Gram-positive bacteria due to its impact on peptidoglycan production.
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Description
This quiz covers the essential structure and function of bacterial cells, focusing on key characteristics and shapes. It includes definitions and classifications of bacteria, important for understanding microbiology. Ideal for students studying prokaryotic organisms.
